1. Field of the Invention
The present invention relates to a cornea shape measuring instrument for measuring the shape of a cornea of a subject's eye for optometry in ophthalmological clinics, optician's shops, or the like.
2. Description of the Related Art
Conventionally, an instrument is known which projects a plurality of concentric ring-shaped targets toward a cornea of a subject's eye, and measures the distribution of the cornea refractive power by analyzing the shape of an image reflected by the cornea. The results of the measurements are output by a printer or the like. The results of the measurements output by the printer are used in optician's shops as prescription data for contact lens, or in ophthalmological clinics as data for orthokeratology.
Japanese Patent Application Laid-open No. Hei 8-98802 discloses an instrument that the refractive power distribution map of the cornea (hereinafter, simply referred to as "a distribution map") in relation to the position of the pupil and the cornea, thereby making it possible to easily understand the positional relationship between the distribution map and the pupil or the cornea.
By the way, in the instrument disclosed in Japanese Patent Application Laid Open No. Hei 8-98802, as illustrated in FIG. 1, circular figures which designate the shape of the pupil image Ep's or that of the cornea margin image Ei' are generated by image recognition process, and these figures are superimposed on the distribution map. Therefore, an operator can correctly understand the positional relationship between the distribution map and the eye by referring to the superimposed image displayed on the display unit. However, since an anterior ocular segment image itself is not displayed on the display unit, there is a problem that the operator can not grasp with reality the positional relationship.